1. Field
Embodiments of the present invention relate to the electronics manufacturing industry and more particularly to the process of plasma etching features in carbonaceous layers.
2. Discussion of Related Art
As the feature size of the device patterns get smaller than 100 nm, the critical dimension (CD) requirement of features becomes a more important criterion for stable and repeatable device performance. Allowable CD variation across a substrate has also scaled with the scaling of feature CD. For example, across a 300 mm diameter substrate, some applications may demand a 3-sigma of less than 10 nm for a target CD averaging about 80 nm.
Also, with lateral dimensions scaling faster than vertical dimensions, because of issues such as device capacitance, high aspect ratios (HAR) are now prevalent in the industry. When such demanding aspect ratios and CD control are compounded with requirements of high etch selectivity, sidewall smoothness and high tool throughput, the process window for any hardware configuration can become very small. In many situations, a small process window can be found only when a number of process gases are incorporated into a complex etchant gas mixture combined with extreme hardware settings, such as very high RF bias powers, to achieve a fragile balance between sidewall passivation, etch rate and mask selectivity. However, such small process windows typically suffer from performance limitations which cannot be tuned out of the etch process with known means.